Regulation 5-1.3
The requirement that applied trim values shall coincide in all stability
information intended for use on board is intended to address initial stability
calculations as well as those that may be necessary during the service life of the
ship.
Regulation 5-1.4 (see also regulation 7.2)
1 Linear interpolation of the limiting values between the draughts
ds, dp and dl is only
applicable to minimum GM values. If it is intended to develop curves of maximum
permissible KG, a sufficient number of KMT values for
intermediate draughts should be calculated to ensure that the resulting maximum
KG curves correspond with a linear variation of GM. When light service
draught is not with the same trim as other draughts, KMT for draughts
between partial and light service draught should be calculated for trims interpolated
between trim at partial draught and trim at light service draught.
2 In cases where the operational trim range is intended to exceed ±0.5% of L, the
original GM limit line should be designed in the usual manner with the deepest
subdivision draught and partial subdivision draught calculated at level trim and
estimated service trim used for the light service draught. Then additional sets of
GM limit lines should be constructed on the basis of the operational range of
trims which is covered by loading conditions for each of the three draughts
ds, dp and dl ensuring
that intervals of 1% L are not exceeded. The sets of GM limit lines are
combined to give a single envelope limiting GM curve. The effective trim range of
the curve should be clearly stated.
3 If multiple GM limiting curves are obtained from damage stability calculations
of differing trims in accordance with regulation 7, an envelope curve covering all
calculated trim values should be developed. Calculations covering different trim values
should be carried out in steps not exceeding 1% of L. The whole range including
intermediate trims should be covered by the damage stability calculations. Refer to the
example showing an envelope curve obtained from calculations of 0 trim and 1% of
L.
4 Temporary loading conditions may occur with a draught less than the light service
draught dl due to ballast water exchange requirements, etc. In these
cases, for draughts below dl, the GM limit value at
dl is to be used.
5 Ships may be permitted to sail at draughts above the deepest subdivision draught
ds according to the International Convention on Load Lines,
e.g. using the tropical freeboard. In these cases, for draughts above
ds the GM limit value at ds is to be
used.
Regulation 5-1.5
There could be cases where it is desirable to expand the trim range, for instance around
dp. This approach is based on the principle that it is not
necessary that the same number of trims be used when the GM is the same
throughout a draught and when the steps between trims do not exceed 1% of L. In
these cases there will be three A values based on draughts s1,
p1, l1 and s2, p2, l2 and
s2, p3, l2. The lowest value of each partial index
As, Ap and Al across these
trims should be used in the summation of the attained subdivision index A.
Regulation 5-1.6
This provision is intended to address cases where an Administration approves an
alternative means of verification.